Frederick Feathers had denied murdering Harry Gurney in October last year. His plea of guilty to manslaughter was rejected.
The boy died after a previously unexplained fracture to his skull was widened by further head injuries. Feathers admitted in court that he had 'snapped' when Harry would not stop crying and had shaken him violently and thrown him on the bed, where 'his head came in contact with a wall'.
The jury heard that a Barking social services case conference was called after Harry recieved his initial skull fracture. It returned the baby to his mother, Joanne Gurney, and Feathers, despite police opposition. That was a week before Harry was murdered.
DC Robert Hosking, an officer from the Barking Child Protection Team, said that his anxieties were 'overruled' by Bula Biswas, a senior social worker with the London Borough of Barking.
He said her words would always remain with him - 'I am not in the habit of breaking up a bond between young mothers and their babies'.
Outside court, DI David Williams, of the Barking Child Protection Team, said that closer supervision might have saved the baby's life. 'Alarm bells were ringing in Harry's case but were ignored.'
After sentence was passed, Ms Gurney shouted at the jury: 'You are idiots.' Outside court she said: 'I am sticking by Fred. I know he didn't mean to do it.'
Harry was born 10 weeks premature on 9 June 1991. He weighed only 3lb (1.36kg) and spent 10 weeks in hospital. Six weeks after being discharged he was back in hospital with a stomach disorder.
An X-ray revealed deformity to two ribs. On 12 October, a day after his admission, his mother took him home against medical advice.
On 20 October, just nine days after going home, the baby was taken back to hospital semi-conscious. Doctors found a severe skull fracture and the Barking Child Protection Team was called.
When the baby was released three days later, police enforced a protection order to win time to continue inquiries. But their appeals to social workers to place the boy on the 'at risk' register were rejected.
On 25 October, a GP examined Harry and said that he was 'fine'. Five days later Ms Gurney appealed for help to neighbours after Feathers inflicted the fatal injuries. By the time Harry reached hospital, he was in a coma. The next day, 31 October, doctors switched off his life-support machine.
Yesterday, the Old Bailey jury returned a unanimous verdict after two hours.
Sentencing Feathers, of Barking, east London, Judge Lawrence Verney, said: 'Because of your age there is only one sentence that the court can pass and I see no value in making any comment on this case beyond your own comment of the awfulness of what you did. The sentence is and must be custody for life.'
Initially, Feathers, who buried his head in his hands, will serve his sentence in youth custody. His counsel, Neil Taylor QC, told the jury that Feathers was not a baby murderer but a man who had lost control.
He said that it was Feathers who had persuaded his 19-year-old girlfriend not to have an abortion while she was pregnant with Harry by another man.
Neil Walker, Barking and Dagenham's director of social services, said: 'It's always easy with hindsight to scapegoat the professionals but there was only one culprit . . . We and the other agencies involved believed the decision (to return the child home) was right at the time.'
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